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  Systems and methods for plasma processing of microfeature workpiecesRelated Patent Categories: Semiconductor Device Manufacturing: Process, With Measuring Or TestingThe Patent Description & Claims data below is from USPTO Patent Application 20070037300. Brief Patent Description - Full Patent Description - Patent Application Claims
TECHNICAL FIELD [0001] The present invention is directed to systems and methods for plasma processing of microfeature workpieces. BACKGROUND [0002] Plasma-based processes, such as plasma enhanced physical vapor deposition, plasma enhanced chemical vapor deposition, plasma etching, plasma immersion ion implantation, and conventional ion implantation, are used in the manufacturing of workpieces having microfeatures. During plasma processes, the plasma density and other plasma parameters must be tightly controlled to produce workpieces within specification. For example, the implant dose of an ion implanter depends on the ion density of the ion source, and the film deposition rate of a physical vapor deposition tool also depends on the ion density. [0003] Conventional devices for measuring plasma parameters include a Langmuir probe. For example, FIG. 1 schematically illustrates a conventional plasma processing system 1 with a Langmuir probe 20. The system 1 further includes a processing vessel 2, a microwave transmitting window 4, and a microwave generator 6. The microwave generator 6 has a wave guide 8 and an antenna 10 positioned so that microwaves radiated by the antenna 10 propagate through the window 4 and into the processing vessel 2 to produce a plasma. The Langmuir probe 20 is inserted into the vessel 2 between process steps to measure plasma parameters. Specifically, a voltage is applied to the probe 20 and scanned from negative to positive while the current is measured. The plasma parameters can be extracted from the relationship between the voltage and current. For example, the ion density can be determined from the ion saturation current (also called a Bohm current I.sub.B) when the scanning voltage is negative. Specifically, the ion density n.sub.i can be calculated by the following equation when the scanning voltage is negative: n i = 2 q .times. I B A eff .times. M eff kT e in which I.sub.B is the ion saturation current collected by the probe 20 under a negative voltage, q is the ion or electron charge, A.sub.eff is the effective area of the probe 20, kT.sub.e is the electron temperature in units of eV, and M.sub.eff is the effective ion mass. [0004] The electron density, which should be generally equal to the ion density in a quiescent plasma, can be calculated from the electron saturation current when the scanning voltage is positive. Specifically, the electron density n.sub.e can be calculated by the following equation when the scanning voltage is positive: n e = 2 q .times. I esat A eff .times. M e kT e in which I.sub.esat is the electron saturation current collected by the probe 20 when the positive scanning voltage equals the plasma potential V.sub.P, q is the ion or electron charge, A.sub.eff is the effective area of the probe 20, kT.sub.e is the electron temperature in units of eV, and M.sub.e is the electron mass. The electron temperature T.sub.e and the plasma potential V.sub.P can be determined from the slope of the electron current and the knee of the electron saturation current, respectively. [0005] One drawback of the Langmuir probe is that the probe cannot measure the plasma parameters in situ and in real time during processing because the probe interferes with the plasma. Specifically, the probe introduces contamination into the vessel and obstructs ingress and egress of the workpiece from the vessel. Another drawback of the Langmuir probe is that the probe cannot measure nonequilibrium plasma such as pulsed glow discharge or steady state plasma With a high voltage pulse. During pulsed plasma processes, the dynamic sheath of the plasma expands and may touch the probe if the probe is too close to the cathode. Therefore, the plasma parameters cannot be measured properly. Another issue is that during the high voltage pulse, the secondary electrons emitted from the cathode can be collected by the probe, which alters the current-voltage characteristics. [0006] Yet another drawback of the Langmuir probe is the measurements can be inaccurate for several reasons. First, the probe draws current from the plasma, which causes significant perturbation in the plasma. Second, if the system includes a radio-frequency generator or magnetron assembly, the radio-frequency or magnetic interference can affect the measurements. Third, the measurements can be affected by sputtering, etching, and/or deposition phenomena depending on the plasma species and process conditions. Fourth, the probe does not measure the parameters of the plasma during workpiece processing, but rather before and/or after processing the workpiece. Accordingly, there is a need to improve the process of measuring plasma parameters. BRIEF DESCRIPTION OF THE DRAWINGS [0007] FIG. 1 schematically illustrates a conventional plasma processing system with a Langmuir probe. [0008] FIG. 2 is a schematic cross-sectional view of a plasma deposition system for processing a microfeature workpiece in accordance with one embodiment of the invention. [0009] FIG. 3 is a flow chart of a method for determining a parameter of a plasma in accordance with one embodiment of the invention. [0010] FIG. 4 illustrates the optical emissions spectrum measured at a specific distance from a workpiece during one example of a process performed in accordance with an embodiment of the invention. [0011] FIG. 5 illustrates the measured intensity of several wavelengths at different distances from the workpiece during one example of a process performed in accordance with an embodiment of the invention. [0012] FIG. 6 illustrates the optical emissions spectrum measured at a specific distance from a workpiece during an example of another process performed in accordance with an embodiment of the invention. [0013] FIG. 7 illustrates the measured intensity of several wavelengths at different distances from the workpiece during an example of another process performed in accordance with an embodiment of the invention. DETAILED DESCRIPTION A. Overview [0014] The following disclosure describes various embodiments of systems and methods for plasma processing of microfeature workpieces. Several embodiments of such systems and methods monitor the plasma in situ while processing a workpiece without contaminating or otherwise affecting the plasma. Several embodiments of systems and methods in accordance with the invention can provide information regarding the ion density or other parameters of the plasma for controlling the plasma process [0015] An embodiment of one method in accordance with the invention includes generating a plasma in a chamber while a microfeature workpiece is positioned in the chamber, measuring optical emissions from the plasma, and determining a parameter of the plasma based on the measured optical emissions. The parameter can be an ion density, an electron density, or another parameter of the plasma. Measuring optical emissions from the plasma may include (a) determining an intensity of the optical emissions at a plurality of wavelengths from a first region of the plasma spaced apart from the microfeature workpiece by a first distance, and (b) determining an intensity of the optical emissions at a plurality of wavelengths from a second region of the plasma spaced apart from the microfeature workpiece by a second distance different than the first distance. [0016] In another embodiment, a method includes generating a plasma in a chamber, depositing material onto a microfeature workpiece in the chamber, and monitoring in real time a parameter of the plasma in the chamber while depositing material onto the microfeature workpiece. The material can be deposited onto the workpiece by plasma enhanced atomic layer deposition (ALD), plasma enhanced chemical vapor deposition (CVD), plasma etching, plasma immersion ion implantation, conventional ion implantation, and/or other processes. Monitoring the parameter of the plasma can include measuring optical emissions from the plasma and estimating a dimension of a sheath of the plasma based on the optical emissions. [0017] Another aspect of the invention is directed to systems for processing microfeature workpieces. In one embodiment, a system includes a plasma chamber coupleable to a source of gas, a workpiece support positioned within the plasma chamber and configured to carry a microfeature workpiece, an energy source positioned to generate a plasma within the plasma chamber, and a detector positioned external to the plasma chamber for measuring optical emissions from the plasma in the plasma chamber. The detector may include an optical emissions spectrometer and a sensor head operably coupled to the spectrometer. The sensor head can be movable relative to the plasma chamber. [0018] In another embodiment, a system includes a plasma chamber, an energy source positioned to impart energy to atoms within the plasma chamber, a detector for measuring optical emissions from a plasma in the plasma chamber, and a controller operably coupled to the detector and configured to monitor in real time a parameter of the plasma based at least in part on a signal received from the detector while processing a microfeature workpiece in the chamber. The controller can include a computer-readable medium having instructions to perform one or more of the above-noted methods. [0019] Many specific details of the invention are described below with reference to systems for depositing materials onto microfeature workpieces, which specifically include implanting or otherwise introducing ions and/or other materials into workpieces. The term "microfeature workpiece" is used throughout to include substrates upon which and/or in which microelectronic devices, micromechanical devices, data storage elements, read/write components, and other features are fabricated. For example, microfeature workpieces can be semiconductor wafers (e.g., silicon or gallium arsenide wafers), glass substrates, insulative substrates, and many other types of materials. The microfeature workpieces typically have submicron features with dimensions of a few nanometers or greater. Furthermore, the term "gas" is used throughout to include any form of matter that has no fixed shape and will conform in volume to the space available, which specifically includes vapors (i.e., a gas having a temperature less than the critical temperature so that it may be liquefied or solidified by compression at a constant temperature). Several embodiments in accordance with the invention are set forth in FIGS. 2-7 and the following text to provide a thorough understanding of particular embodiments of the invention. A person skilled in the art, however, will understand that the invention may have additional embodiments, or that the invention may be practiced without several of the details of the embodiments shown in FIGS. 2-7. Continue reading... Full patent description for Systems and methods for plasma processing of microfeature workpieces Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Systems and methods for plasma processing of microfeature workpieces patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Systems and methods for plasma processing of microfeature workpieces or other areas of interest. ### Previous Patent Application: Method and apparatus for monitoring precision of wafer placement alignment Next Patent Application: Apparatus and method of illuminating the surface of a wafer in a wafer inspection system Industry Class: Semiconductor device manufacturing: process ### FreshPatents.com Support Thank you for viewing the Systems and methods for plasma processing of microfeature workpieces patent info. IP-related news and info Results in 0.23804 seconds Other interesting Feshpatents.com categories: Computers: Graphics , I/O , Processors , Dyn. Storage , Static Storage , Printers |
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